Vehicle controller, method, and program for steering reaction during manual driving for returning to a preset route

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2022-210552, filed Dec. 27, 2022, the contents of which application are incorporated herein by reference in their entirety.

The present disclosure relates to a controller, a method, and a program for controlling a vehicle operated along a preset operation route.

Examples of documents indicating the technical level in the technical field related to the present disclosure include JP2010-513123A and JP2001-151137A. For example, JP2010-513123A discloses a method for generating a target trajectory adapted to a surrounding situation and adjusting a steering system so that a vehicle follows the target trajectory. According to the method, a permissible travel path is assigned to the target trajectory and basic steering torque is generated which guides the vehicle along the permissible travel path. If the vehicle leaves the permissible travel path, steering guidance torque acting on the vehicle in the direction of the permissible travel path is superimposed on the basic steering torque.

By the way, in a vehicle where manual operation by a driver is allowed, steering may be performed toward a road that deviates from an operation route. The techniques described in the above patent documents are techniques for operating a vehicle at a preferable position in a lane by assistance for steering, but are not techniques for preventing the vehicle from deviating from an operation route.

The present disclosure has been made in view of the above problem. An object of the present disclosure is to prevent a vehicle from traveling toward a road deviating from a preset operation route when the vehicle is operated by manual driving.

The present disclosure provides a vehicle controller, a vehicle control method, and a vehicle control program as a vehicle control technique for achieving the above object.

The vehicle controller of the present disclosure includes at least one processor and a memory communicatively coupled to the at least one processor and storing a plurality of executable instructions. The plurality of executable instructions is configured to cause at least one processor to perform the following processing. The processing includes acquiring a preset operation route, causing the vehicle to travel along the operation route in one of an autonomous driving mode and a manual driving mode, and generating steering torque in a direction of returning the vehicle to the preset operation route in response to detection of steering toward a road deviating from the preset operation route during operation in the manual driving mode. The autonomous driving mode is a mode in which the vehicle is operated by autonomous driving, and the manual driving mode is a mode in which the vehicle is operated by manual driving in which at least steering is manually performed by a driver.

The vehicle control method of the present disclosure is a method for controlling a vehicle by a computer. The vehicle control method includes acquiring a preset operation route, causing the vehicle to travel along the preset operation route in one of an autonomous driving mode and a manual driving mode, and generating steering torque in a direction of returning the vehicle to the operation route in response to detection of steering toward a road deviating from the preset operation route during operation in the manual driving mode.

The vehicle control program of the present disclosure is configured to cause a computer to perform the vehicle control method described above. In other words, the vehicle control program of the present disclosure is configured to cause a computer to function as the vehicle controller described above by being executed by the computer. The vehicle control program of the present disclosure may be stored in a non-transitory computer-readable storage medium or may be provided via a network.

According to the vehicle control technique of the present disclosure, the autonomous driving mode may be switched to the manual driving mode in response to detection of intervention in steering by the driver during operation in the autonomous driving mode. In this case, the generation of the steering torque in the direction of returning the vehicle to the preset operation route may be suppressed until a preset time elapses from the detection of the intervention or until the vehicle moves a preset distance from the detection of the intervention. According to this, when the driver intentionally intervenes in steering, the generation of steering resistance that disturbs the driver's intention is suppressed.

According to the vehicle control technique of the present disclosure, when the driver performs steering toward a road deviating from the preset operation route during operation in the manual driving mode, the steering torque in the direction of returning the vehicle to the preset operation route is generated. Thus, when the vehicle is operated along the preset operation route, the vehicle is prevented from traveling on a road deviating from the preset operation route during the operation by manual driving.

The vehicle control method according to the embodiment of the present disclosure is applied to a vehicle capable of autonomous driving at level 2 or higher in the definition of the autonomous driving level of the SAE. Hereinafter, the vehicle according to the present embodiment means a vehicle capable of performing autonomous driving to which the vehicle control method according to the present embodiment is applied.

The vehicles according to the present embodiment are used to provide a transport service by autonomous driving in an area (hereinafter referred to as an Lv4 service area) in which a traveling environment condition for autonomous driving of level 4 is satisfied. That is, the vehicle according to the present embodiment is a vehicle capable of autonomous driving at level 4. However, as shown in, the Lv4 service area is a limited area, and there are many cases where garages in which vehicles are parked and transfer points with surrounding transportation facilities such as stations are located outside the Lv4 service area. Further, the Lv4 service area does not exist as one continuous area, but a plurality of Lv4 service areas exist discretely. In sections connecting garages, stations, and the like to Lv4 service areas and sections connecting two Lv4 service areas, operation routes for operating vehicles are set. The vehicles according to the present embodiment move on the operation route outside the Lv4 service area by autonomous driving or manual driving at level 2.

In the Lv4 service area, since the subject of driving the vehicles is the vehicles themselves, there is no possibility of making a wrong road. In the autonomous driving at level 2, steering is assisted. If an operation route leading to the Lv4 service area is set as the target route, steering is autonomously performed so as to move the vehicle along the operation route. Therefore, it may be considered that there is no possibility that the vehicle enters a road deviated from the operation route while the driver receives the support by the autonomous driving of level 2.

However, when the driver intervenes in the steering for some reason, the autonomous driving at level 2 is cancelled and can be switched to the manual driving. In general, in the manual driving after the autonomous driving of level 2 is cancelled, steering is performed according to the driver's judgment, and thus there is a concern that a wrong road may occur. Incorrect routes cause delays in the operation. In an area outside the Lv4 service area, localization based on map information is performed in order to detect entry into the Lv4 service area. However, if the vehicle enters a road without map information by mistake, it is necessary to perform localization again.

In the following description, a mode in which the vehicle is operated by autonomous driving at level 2 is referred to as an autonomous driving mode, and a mode in which the vehicle is operated by manual driving is referred to as a manual driving mode. In the vehicle control method according to the present embodiment, during traveling in the manual driving mode, the driver's free steering is not allowed, but a restriction is applied to the steering to prevent the vehicle from traveling on a road that deviates from the operation route. Hereinafter, the steering control performed during operation in the manual driving mode will be specifically described with reference toand.

In, the vehicle control method according to the present embodiment is applied to a vehicle. The vehicleis operated in the manual driving mode and is approaching a point at which the branch roadbranches off to the right from the main road. In the case shown in, the branch roadis the operation route of the vehicle, and the main roadbeyond the branch point is a road that deviates from the operation route. In the case shown in, the main roadis the operation route of the vehicle, and the branch roadis a road that deviates from the operation route.

In the case shown in, in order to drive the vehiclealong the driving route, the vehiclemust be driven towards the branch road. The steering amount expected for the vehicleto proceed to the branch roadcan be calculated from the map information, specifically, the road shape of the branch point at which the branch roadbranches off from the straight roadand the attitude of the vehicle. When the steering amount by the manual operation of the driver satisfies the expected steering amount, the vehicleproceeds to the branch roadalong the operation route.

However, when the steering amount by the manual operation is different from the expected steering amount, specifically, when the steering in the right direction is not performed and the current steering amount is maintained, the vehiclecontinues to travel on the main roadand deviates from the operation route. Therefore, in such a case, a clockwise steering torque is applied to the vehicle steering device operated by the driver, specifically, the steering wheel. The application of the steering torque urges the driver to steer the vehiclerightward, and the driver operates the steering wheelso as to move the vehicleto the branch road. Thus, the vehicleis prevented from deviating from the operation route. In a case where the branch road is branched to the left from the main road, a counterclockwise steering torque is applied to urge the driver to steer to the left.

In the case shown in, in order to operate the vehiclealong the operation route, it is necessary to cause the vehicleto continue to travel on the main road. The steering amount expected for the vehicleto continue traveling on the main roadcan be calculated from the map information, more specifically, the road shape of the main roadand the attitude of the vehicle. When the steering amount by the manual operation of the driver satisfies the expected steering amount, the vehiclecontinues to travel on the main roadalong the operation route.

However, when the steering amount by the manual operation is different from the expected steering amount, specifically, when the steering in the right direction is performed without maintaining the current steering amount, the vehiclemoves toward the branch roadand deviates from the operation route. Therefore, in such a case, a counterclockwise steering torque is applied to the steering wheelso as to counteract the clockwise steering torque applied to the steering wheelby the driver. This steering torque acts as resistance when the driver operates the steering wheelto steer the vehiclein the right direction, and urges the driver to maintain the current steering amount. Thus, the vehicleis prevented from deviating from the operation route. In the case where the branch road is branched to the left from the main road, the counterclockwise steering torque is applied so as to act as resistance against the leftward steering by the driver.

As described above, in the vehicle control method according to the present embodiment, during the operation of the vehiclein the manual driving mode, the steering torque for the steering assist is generated according to a rule different from that during the operation of the vehiclein the autonomous driving mode. In the autonomous driving mode, steering torque for steering assist is generated so that the vehicletravels along the target trajectory. The target trajectory is a trajectory through which the vehicleshould pass in order to cause the vehicleto travel along the operation route, and is set on the basis of information on obstacles around the vehicle. On the other hand, the steering torque generated in the manual driving mode is intended to prevent the driver from selecting a road different from the driving route. Therefore, in the manual driving mode, in a case where the vehicleis about to move to a road that deviates from the operation route at a place where there are a plurality of road options such as a branch point or an intersection, steering torque in a direction to return the vehicleto the operation route is generated.

When the driver intervenes in steering in the autonomous driving mode, switching from the autonomous driving mode to the manual driving mode is performed. The intervention in the steering by the driver is performed, for example, when a road different from the operation route is selected by a clear intention of the driver. If the above-described steering torque is generated at this time, the driver cannot operate the steering wheelas he or she desires, and there is a possibility that the intervention operation is hindered.

As a measure against the above problem, in the vehicle control method according to the present embodiment, when the driver's intervention in the steering is detected in the autonomous driving mode, the application of the steering torque for the steering assist is stopped until a preset time elapses. Hereinafter, in the vehicle control method according to the present embodiment, to the manual driving mode in the vehicle control method according to the present embodiment will be specifically described with reference to.

In, the state of the vehicleduring operation is depicted in time series. At time T, the vehicleis traveling on the main roadin the autonomous driving mode. In the autonomous driving mode, steering assistance is performed so as to cause the vehicleto travel along a target trajectory set on the operation route.

At time T, the driver operates the steering wheelto direct the vehicletoward the branch road. That is, the driver intervenes in the steering. The driving mode is switched from the autonomous driving mode to the manual driving mode in response to an intervention from the driver. At the same time as the operation mode is switched to the manual operation mode, a timer set to a preset time (for example, several seconds to several tens of seconds) is started.

At time T, the vehicledeviates from the main road, which is an operation route, and advances toward the branch road. However, until the value of the timer becomes 0, the steering torque in the direction of returning the vehicleto the operation route is not applied even when the vehicleis out of the operation route. That is, the steering assist for the manual driving mode is turned off until the value of the timer becomes 0 from the preset time.

At time T, the value of the timer becomes 0. Thereafter, the steering assist for the manual driving mode is turned on. Therefore, when the vehicleis about to move to a road that deviates from the operation route, steering torque in a direction to return the vehicleto the operation route is generated. Before the value of the timer becomes 0, the navigation device searches again for an operation route to the destination and sets a new operation route passing through the branch road.

Since the steering control as described above is performed immediately after the switching of the driving mode, the generation of the steering resistance disturbing the intention of the driver is suppressed with respect to the intentional intervention of the driver in the steering.

The procedure of the vehicle control method according to the present embodiment can be shown by a flowchart.is a flowchart illustrating a procedure of the vehicle control method according to the present embodiment.

In step S, the driving mode of the vehicleis determined. When the current driving mode is the autonomous driving mode, the procedure proceeds to step S.

In step S, the processing of the autonomous driving of level 2 is continued. When the driver's intervention in steering is detected during operation in the autonomous driving mode, the driving mode is changed from the autonomous driving mode to the manual driving mode. After step Sis performed, the procedure ends.

If it is determined in step Sthat the current driving mode is the manual driving mode, the procedure proceeds to step S.

In step S, it is determined whether or not a preset time has elapsed from the immediately preceding intervention by the driver in the steering. That is, it is determined whether or not a preset time has elapsed since switching from the autonomous driving mode to the manual driving mode. If the preset time has not elapsed, the procedure ends without performing the remaining steps.

If it is determined in step Sthat the preset time has already elapsed, the procedure proceeds to step S.

In step S, a steering amount of the vehicular steering device is acquired. A specific example of the vehicle steering device is the steering wheel, and a specific example of the steering amount is a steering angle. Next, the procedure proceeds to step S.

In step S, the expected value of the steering amount is calculated from the road shape of the operation route and the current attitude of the vehicle. The expected value of the steering amount is a steering amount expected to cause the vehicleto travel along the operation route. Next, the procedure proceeds to step S.

In Step S, the steering amount acquired in Step Sis compared with the expected value of the steering amount calculated in Step Sto determine whether or not the steering amount is insufficient with respect to the expected value. Specifically, when the steering amount is smaller than the expected value and the difference therebetween exceeds a threshold value A, it is determined that the steering amount is insufficient with respect to the expected value. When the steering amount is insufficient with respect to the expected value, the procedure proceeds to step S.

In step S, torque for guiding the driver's steering operation is generated so that the vehiclefollows the operation route. That is, the steering control as illustrated inis performed. After step Sis performed, the procedure ends.

When it is determined in step Sthat the steering amount is not insufficient with respect to the expected value, the procedure proceeds to step S.

In Step S, the steering amount acquired in Step Sis compared with the expected value of the steering amount calculated in Step Sto determine whether or not the steering amount exceeds the expected value. Specifically, when the steering amount is larger than the expected value and the difference therebetween exceeds a threshold value B, it is determined that the steering amount is excessive with respect to the expected value. When the steering amount is excessive with respect to the expected value, the procedure proceeds to step S.

In step S, torque acting as a steering resistance of the driver is generated so that the vehiclemoves along the operation route. That is, the steering control as illustrated inis performed. After step Sis performed, the procedure ends.

Next, a vehicle controller according to the present embodiment will be described.

is a block diagram showing a configuration of the vehicle controller according to the present embodiment. The vehicle controlleraccording to the present embodiment is a computer that performs the above-described vehicle control method. The vehicle controllerincludes a navigation device, an autonomous driving device, a steering assist device, an intervention determination device, a first selector, a state machine, a second selector, and a vehicle driving device. These are functions of the vehicle controllerthat are implemented by executing preset multiple instructions by at least one processor that physically configures the vehicle controller.

The navigation devicegenerates an operation route based on the operation plan of the vehicle. The operation plan includes, for example, information such as a departure point, a scheduled departure time, a destination, a scheduled arrival time, a relay point, and a relay point passing time. The operation plan is defined in advance and registered in the memory. Alternatively, the operation plan is distributed by wireless communication from a management server that manages the operation of the vehicle. The navigation devicedistributes the latest operation route to the autonomous driving deviceand the steering assist deviceeach time the operation route is updated. The navigation devicemay be a separate device physically independent of the vehicle controller.

The autonomous driving deviceacquires sensor information from a recognition sensor mounted on the vehicle, and performs recognition and determination based on the sensor information. Then, based on the result of the recognition and the determination, a target trajectory along the operation route is generated. The target trajectory is represented by a target position of the vehicleand a target speed or a target acceleration at the target position, and is updated every time the vehiclemoves. The autonomous driving devicetransmits the target trajectory to the vehicle driving device. Note that the autonomous driving deviceis always operating regardless of whether it is in the autonomous driving mode or the manual driving mode.

The steering assist devicecalculates a steering amount expected to operate the vehiclealong the operation route based on the road shape of the operation route and the current attitude of the vehicle. Then, the actual steering amount is compared with the expected steering amount. When the actual steering amount is insufficient with respect to the expected steering amount, for example, when the vehicleis likely to travel straight at a place where a right turn or a left turn is required, the steering assist deviceurges the driver to turn right or left by applying steering torque to the vehicle steering device. When the actual steering amount is excessive with respect to the expected steering amount, for example, when the vehicleis likely to turn right or left at a place where straight traveling is required, the steering assist deviceurges the driver to go straight by adjusting the steering torque applied to the vehicle steering deviceto generate steering resistance. Note that the steering assist deviceis always operating regardless of whether it is in the autonomous driving mode or the manual driving mode.

The vehicle driving devicedrives the vehicleby operating an actuator mounted on the vehicle. The vehicle driving deviceis selectively connected to one of the autonomous driving deviceand the vehicle steering device. When connected to the autonomous driving device, the vehicle driving deviceoperates the driving actuator, the braking actuator, and the steering actuator based on the target trajectory generated by the autonomous driving device. When connected to the vehicle steering device, the vehicle driving deviceoperates the steering actuator in accordance with the steering amount input from the vehicle steering device. At this time, the vehicle driving deviceoperates the driving actuator and the braking actuator in accordance with the operation amount of the accelerator pedal or the brake pedal by the driver.

The intervention determination devicereceives the steering amount from the vehicle steering device. When a change in the steering amount exceeding a threshold is detected, the intervention determination devicedetermines that the driver intervenes in the steering. The intervention determination devicerecords the time at which it is determined that there is intervention as an intervention time. The intervention determination devicenotifies the first selectorof the determination result of the presence or absence of intervention and the intervention time. In addition, the intervention determination devicenotifies the state machineof the determination result of the presence or absence of the intervention.

The first selectoris provided in a transmission line of the steering torque from the steering assist deviceto the vehicle steering device. The first selectorconnects or disconnects the transmission line based on the determination result of the presence or absence of intervention and the intervention time notified from the intervention determination device. When it is determined that there is intervention, the first selectorblocks the transmission line and blocks transmission of the steering torque applied from the steering assist deviceto the vehicle steering device. Even after the intervention is finished, the first selectorblocks the transmission line until a preset time elapses from the immediately preceding intervention. Then, after it is determined that there is no intervention and a preset time has elapsed from the immediately preceding intervention, the first selectorconnects the transmission line and transmits the steering torque applied from the steering assist deviceto the vehicle steering device.